Never seen water getting in the trunk,How much moister are you referring to?
(1) You should have a rubber seal all around the lower half of the trunk surface, were the lid comes in contact with. It is glued down.
(2) do you have a luggage rack on the lid moister could be getting in through there.
(3) the lower half is comprised of two pieces, the screws that hold the two half’s together are under the glued down seal from (1) and the lower bolts to the hinges.
I've seen as much as a 1/4 cup. I'll check the seal and luggage rack . TY